How to treat banksia verticillata brown leaves?

[Fintan]

We bought a Banksia verticillata and planted 2-3 months ago. Since planting it hasn’t grown, and started to shrink and get brown leaves. At first, I thought it just needed more watering as summer, however this hasn’t improved things at all.

Upon further reading I think it might be due to poor drainage and possible root rot. The soil does seem somewhat compact and when I water, there is normally a pool of water that sits on top and takes a while to soak in. 

Can you please recommend the steps I need to take to try and bring this plant back to life? Ideally step by step outline, as I’m a beginner gardener 🧑‍🌾! 

Thanks a lot. 

  

 

[JacobZ]

Hi @Fintan,

A warm welcome to the Bunnings Workshop community, it is wonderful to have you with us.

It seems likely that your tree is experiencing transplant shock. Transplant shock happens when the plant struggles to adapt after being moved, often due to root disturbance, changes in the environment, or poor soil conditions. Banksias are particularly sensitive to root disturbance because they rely on fine root clusters to absorb nutrients.

You'll want to start by checking the root health of the plant as root rot could be present. Gently dig around the base of the plant and check if the roots are mushy, black, or smell rotten. If so, root rot has set in and your tree may not be salvageable.

If root rot has set in, carefully dig up the plant, keeping as much of the root ball intact as possible, trim off any blackened, mushy, or rotten roots with clean scissors and let the roots air dry before replanting. While the tree is out of the ground, aerate the ground at the bottom of the hole with a garden fork and add gypsum to help break up any clay. Replant in a raised mound with a mix of native potting mix, sand, and small gravel to improve drainage. Water lightly and wait a few days before watering again.

If you check the roots and there is no evidence of root rot, carefully use a hand fork to turn and aerate the soil. Add gypsum and compost at the base of the tree and mix it in. 

Once you've taken these steps, focus on getting the watering schedule correct. You should only be watering around once a week, maybe less depending on the soil. Banksias don't like wet feet, so if you are planning on watering, check the top 5-10cm of soil before proceeding. If it is still moist, wait a few days, if it is dry, water deeply till the soil is soaked then leave it for around a week before checking again.

Allow me to tag our experienced gardeners, @Noelle, @mich1972 and @robchin to see what they think.

Let me know if you have any further questions.

Jacob